Abstract: Systems and methods directed to aldehyde detection are disclosed. An aldehyde detection system may capture aldehydes from a patient breath sample. Aldehydes of the breath sample may be used to form a mobile chromatography phase within an analysis device. The analysis device may include various modules configured to perform a high pressure liquid chromatography process that separates aldehydes according to size. A detection assembly may detect a relative value of the separated aldehydes. The analysis device may be configured to determine an aldehyde score or metric based on the detected aldehydes, which may assist in the diagnosis of certain medical conditions.